Diagnostic immunoassays are typically reliant on a color change or the production of color to reveal a result that is often visible by the human eye. As a result of the human perception and judgment involved, there is significant variance among those interpreting such test results as to whether a color change or other measurable signal has occurred, particularly if the signal is close to a threshold value. There can be, therefore, subjectivity involved in interpreting whether immunoassay results are positive or negative. Moreover, for detection of some analytes present in small quantities, a sufficient color change or color production is not possible for detection by the human eye. Accordingly, there remains a need in the art for an apparatus and a system that objectively analyses a signal from an immunoassay test device, to reduce the error associated with interpreting the result, and to improve the sensitivity of the device by providing an apparatus that can detect a small or weak signal imperceptible to the human eye.